高速列车齿轮箱箱体动应力响应及疲劳可靠性研究

Dynamic Stress Response and Fatigue Reliability of Gearbox Housing for G-Series High-Speed Train

高速列车铸铝合金齿轮箱在服役过程中承受复杂的载荷条件和随机应力。以某新型高速列车齿轮箱为研究对象,结合线路试验分析列车运行速度、电机输出扭矩及线路条件对箱体动应力响应及疲劳强度的影响,利用应力—强度干涉理论建立齿轮箱等效应力—疲劳强度干涉可靠性模型,分析齿轮箱箱体疲劳可靠度与服役里程的关系。结果表明:随着列车运行速度和电机输出扭矩的增大,箱体各测点的应力水平均有不同程度的增大,其中端部吊杆座处的应力变化最为明显;当列车运行速度由200km·h-1增加到400km·h-1时,其最大动应力幅值增大约120%,电机输出扭矩由0变为1400N·m时最大动应力幅值增大约150%。此外,线路条件对箱体等效应力也影响显著。随着列车服役里程的增加,箱体疲劳可靠度不断降低,在一定可靠度下,随着铝合金箱体铸造水平等级的提高,齿轮箱箱体寿命延长,铸造孔径为0.5mm时的服役里程是铸造孔径为0.9mm时的3.8倍。

The cast aluminum alloy gearbox for G-series high-speed train is subjected to complex load conditions and stochastic stresses during service.Taking a new-type gearbox for G-series high-speed train as the research object,the influence of train speed,motor output torque and track condition on the dynamic stress response and fatigue strength of gearbox was analyzed combined with line tests.By means of stress-strength interference theory,an equivalent stress and fatigue strength interference reliability model for gearbox was established,and the relationship between the fatigue reliability of gearbox housing and service mileage was analyzed.Results show that,with the increase of train speed and motor output torque,the stress level at each measuring point on the gearbox housing increases in varying degrees,and the stress change at the seat of end hanger rod is the most obvious.When the train speed increases from200 to 400 km·h-1,the maximum dynamic stress amplitude increases about 120%,while it increases about 150% when the motor output torque changes from 0 to 1 400 N·m.The track condition also has a significant influence on the equivalent stress of the housing.With the increase of the service mileage of the train,the fatigue reliability of the housing decreases continuously.Under the certain reliability,with the improvement of the quality grade of cast aluminum alloy housing,the service life of the gearbox housing can be prolonged,for example,the service mileage can be increased by a factor of 3.8 when the casting pore size changes from 0.9 to 0.5 mm in diameter.